Substance use disorders (SUDs) are classified into two main categories: abuse and dependence, per the American Psychiatric Association Diagnostic and Statistical Manual, 4th edition, Text Revision (DSM-IV-TR; 2000). The DSM-IV-TR also identifies different classes of substances. These are alcohol; amphetamine; caffeine; cannabis; cocaine; hallucinogens; inhalants; nicotine; opioids; phencyclidine; and sedatives, hypnotics, or anxiolytics; and polysubstance (the latter referring to use of at least three classes of substances, but not including caffeine or nicotine, with no one substance predominating). The DSM-IV-TR also describes various important phenomena related to SUD diagnoses, including intoxication, withdrawal, tolerance, and remission. A current diagnosis refers to past-year timeframe; a lifetime diagnosis refers to having met criteria during some one-year period prior to the past year.

Criteria for SUD address various important impacts of substance use. Substance abuse criteria focus on substance-related problems at work or school; in dangerous situations, such as driving; with family and other important relationships; and with the legal system. Substance dependence criteria focus on tolerance, withdrawal; substance-related worsening of physical and/or mental health concerns; inability to control use of the substance; spending large amounts of time finding, using, and recovering from the substance; giving up other activities to use the substance; and continuing to use despite a strong desire to quit. See the DSM-IV-TR for more information.

Substance and Alcohol Disorders

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